(Updated 3:53 p.m.) U.S. Rep. Chris Murphy will formally announce his run for U.S. Sen. Joseph Lieberman’s vacated seat Thursday evening at the Waverly Tavern in Cheshire.

In advance of the formal announce Murphy will hold a conference call with Connecticut reporters Thursday afternoon, according to his spokeswoman Kristen Bossi.

Murphy, the third-term Congressman from the Fifth Congressional District, is the second candidate to enter what is expected to be a crowded field.

It’s no secret Murphy has been thinking about running for Lieberman’s Senate seat. He even has his first campaign video up on his campaign website.

In a press release, Murphy said the decision to run for the Senate wasn’t easy and addressed the issue that he will have to divide his time between the campaign and his constituents in the Fifth District.

“My heart is in the Fifth District, where Cathy and I are raising our son, and my top priority will continue to be doing this job that I love,” Murphy said. “I only take this step because I believe I can be an even stronger voice for change in the United States Senate.”

“What I’ve heard is that people feel that the Senate simply doesn’t work anymore – it’s become an unjustifiable barrier to positive change, and Connecticut needs a fresh, progressive voice there that will push for both policy and institutional reform, ” he added. 

In a conference call Thursday afternoon a few hours before his public appearance in Cheshire, Murphy talked a little bit about why he’s running for the U.S. Senate and what he expects to change if he gets there.

“The filibuster is in dire need of reform,” Murphy said. “We need to reform the way the filibuster is used so that it is not a means of ordinary, everyday resistance to policy, but only used in exceptional circumstances.”

He said he knows firsthand what its like to have one Senator hold up a bill because it’s happening right now to his bill that allows a family to participate in the search of a missing loved one.

“We shouldn’t allow a Senator stop any legislation big or small from moving forward,” Murphy said referring to a rule that allows Senators to put secret holds on bills.

Murphy formally announced his intentions Thursday because he said “it’s the first day this is an open seat,” however, the 37-year-old he also understands the reality of the modern campaign.

The video Murphy released along with his first fundraising letter was filmed this past weekend. He understands it’s important to get out in front and expects he will have to raise at least $10 million or more to compete.

Murphy said he was outspent 2-to1 in when he defeated veteran Congresswoman Nancy Johnson to win his first term, and even in the past campaign close to a $1 million in special interest money was spent in an effort to discredit him.

Republican Linda McMahon spent $50 million on her Senate race against U.S. Sen. Richard Blumenthal and lost. Sources close to McMahon say she hasn’t made up her mind yet, but she is considering it.

Earlier this week former Secretary of the State Susan Bysiewicz announced her intentions to seek the Democratic nomination and U.S. Rep. Joe Courtney, who represents the Second Congressional District, has also expressed an interest in the seat.